Burner

ABSTRACT

A burner for disposing of a high pressure and a low pressure stream of gaseous fuel in which the high pressure fuel passes through an air entrainment nozzle to produce an air/fuel mixture. The flow of the mixture is diverted to produce a low pressure zone into which the low pressure fuel flows. In a modification there is a second entrainment nozzle so that the high pressure fuel enters the low pressure fuel so as to assist its flow.

United States Patent 1 Desty et a1.

[54] BURNER [75] Inventors: Denis Henry Desty, Weybridge; Christopher John Young, Chertsey, both of England [73] Assignee: The British Petroleum Company Limited, London, England [22] Filed: Oct. 6, 1970 [21] Appl. No.: 78,479

[30] Foreign Application Priority Data Nov. 19, 1969 Great Britain ..56,547/69 [51] Int. Cl ..F23q 9/00 [58] Field of Search ..431/284 51 Jan. 9, 1973 [56] References Cited UNITED STATES PATENTS 1,865,983 7/1932 Warner ..43l/284 X 3,419,339 12/1968 Schreter et a1. 3,516,773 6/1970 Rosenberg et al Primary Examiner--Carroll B. Dority, Jr. Attorney-Morgan, Finnegan, Durham & Pine [57] ABSTRACT 2 Claims, 2 Drawing Figures LP FUEL PATENTED JAN 9 I975 SHEET 1 [IF 2 'mv sw'roasz DEN l HENRY DESTY I FIG. 7.

CHR\$TOPHER JOHN vouua EY:W,WIMM&P.M 'THHR ATTORNEYS PATENTEUJAII 9191s 3,709,654

SHEET 2 [IF 2 T LP FUEL INVENTORSZ DEN\$ HENRY DBSTY CHR\STOPHER JOHN yourw BY: Watm HE\ E ATTORNEYS BURNER This invention relates to a burner for disposing of waste combustible gas, and in particular it relates to the disposal of waste petroleum gas.

There are many occasions when the oil industry has to handle a crude petroleum or fraction thereof which has an unacceptably high vapor pressure by reason of the concentration of low molecular weight hydrocarbons, e.g. methane, ethane, propane and butane. it is common practice to reduce the vapor pressure by reducing the concentration of the volatile components and the combustible gas so produced usually has a pressure below 6 kN/m (The pressures represent excess over atmospheric.)

It is not always possible to sell or otherwise make use of combustible gases at low pressure and on occasions they have to be sent to waste. This often gives rise to smokey flames, particularly with butane at pressures below 1.5 kN/m It is an object of this invention to improve this combustion.

According to the invention a burner for disposing of low pressure waste gas comprises a primary fuel inlet adapted to direct a primary fuel gas (originally at high pressure) to flow over a director surface which is shaped so as to cause the primary fuel flow to initiate flow of primary fuel and air towards a secondary fuel inlet which is adapted to supply secondary fuel gas (originally at low pressure) into the flow of primary fuel gas and air.

The invention also includes a modified form of the burner described above which is particularly suitable when it is necessary to burn waste gas at very low pressure, e.g., 0.5 kN/m (2 ins. water gauge), or even less.

According to the modified form of the invention the burner also comprises an auxiliary inlet adapted to direct primary fuel gas to flow over an auxiliary director surface situated in a secondary fuel gas channel and shaped so that the flow of primary fuel creates a low pressure which encourages the flow of secondary fuel towards the secondary fuel inlet and into the flow of primary fuel and air.

It is known that a stream of gas will stick to a suitably shaped surface and a curved surface can deflect a stream of gas and thereby produce a low pressure zone. In the burner according to the invention the initial portion of the director surface is shaped so as to deflect the flow of primary fuel gas and to produce a low pressure zone into which atmospheric air flows.

During the use of the burner the low pressure zone contains gas with high kinetic energy. In order to improve the flow pattern away from the low pressure zone the final portion of the director body is shaped so as to reduce the kinetic energy and increase the pressure of the gas, e.g., the final portion of the director body is tapered so that the flow path for primary fuel gas increases as the cross-section of the director body decreases or tapers.

Preferably the burner comprises a director tube the outer surface of which is the director surface and the bore of which is a secondary fuel gas channel which terminates at the secondary fuel inlet. 1n the modified form of the burner part of the inner surface of the director tube forms the auxiliary director surface.

A burner according to the invention preferably comprises a baffle positioned near the secondary inlet and adapted to deflect the flow of secondary fuel into the flow of primary fuel and air. The baffle encourages mixing and particularly when methane is the high pressure fuel, it helps to stabilize the flame.

The invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 shows a burner according to the invention half in side view and half in cross section, and

FIG. 2 is a cross section of the modified form of the burner shown in FIG. 1.

The burner shown in FIG. 1 comprises a director surface 20 which forms the outer surface of a director tube 10 which has, at its lower end, a primary inlet 11 for supplying primary fuel gas at said lower end, and which has, at its upper end, a secondary inlet 12 for supplying secondary fuel gas at said upper end. During use the primary fuel gas flows over the director surface 20 towards the secondary inlet and this flow initiates flow of fuel and of air surrounding the tube 10 towards the secondary fuel inlet 12. A baffle 17 overlies the director tube 10 and outwardly deflects the flow of air, primary fuel gas and secondary fuel gas so as to encourage mixing.

The director tube 10 has a flat annular base 13 and the primary inlet 11 takes the form of a circular slit formed between the upper terminus of the wall of a primary fuel line 14 and the flat base 13 so that the primary fuel leaves the primary inlet 11 and is supplied to the director surface 20 as a thin horizontal sheet.

The director surface 20 comprises two portions, namely a curved deflector portion 15 at the lower end of the director tube 10, which turns the direction of flow of the primary fuel gas supplied via the primary inlet 11, from horizontal to vertical, and a tapered portion 16 which extends to the secondary inlet 12 and modifies the flow between the deflector portion 15 and the secondary inlet 12.

The shape of the deflector portion 15 is most conveniently specified as the surface of revolution formed by the rotation of a quadrant of a circle about an axis not passing through the center of the quadrant; as shown in the drawing the distance between the axis of rotation and the center of the quadrant is equal to the radius of the quadrant. The shape of the tapered portion 16 is that ofa frustum ofa cone.

As the primary fuel flows around the deflector portion 15 its direction of flow is changed from (initially) horizontal to vertical. This induces a low pressure zone in the surrounding air and hence it induces movement of air as well as primary fuel towards the secondary inlet 12. The tapered portion 16 represents a flow-path of increasing cross sectional area as the cross-section of the director body decreases or tapers, and hence the pressure of the moving gas (fuel and air) increases while the velocity decreases towards the secondary inlet 12.

The secondary fuel gas is conveyed to the secondary inlet by the secondary fuel gas line 18 (which constitutes the bore of the director tube 10 and forms an annular configuration with the primary fuel gas line 14 and is sealingly connected to the upper end of the director tube 10 and to the lower end of the primary fuel gas line 14) and secondary fuel which issues from the secondary fuel line 18 through the secondary inlet gas surrounding the director tube 10, by the baffle 17. The baffle 17 also outwardly deflects the primary fuel and air and this encourages mixing and it also helps to stabilize the flame.

The pressure around the secondary inlet 12 depends upon the rate of flow of primary fuel gas and this flow rate can be adjusted to minimize any tendency to create a back pressure on the line 18.

In a laboratory test a prototype burner as illustrated in FIG. 1 was used to dispose of low pressure butane using methane as the primary fuel. Burner dimensions and experimental conditions are given in the following table.

Burner Dimensions Length 15 cm Max. Diameter 7 cm Experimental Conditions Pressure of Butane 6 kN/m Pressure of Methane 200 kN/m Flow rate of Butane 1 l Kg/h Flow rate of Methane 230 Kg/h FIG. 2 shows a modified form of the burner illustrated in FIG. 1. This burner includes all the features of the burner already described. These features have been given the same reference numerals and no further description will be given.

The modification comprises an auxiliary director surface 30 situated within and forming an inner wall of the director tube so as to provide the secondary fuel gas channel 21. The channel 21 forms the bore of the deflector tube 10 and serves as an extension to the secondary fuel gas line 18 which, in this modification, has its upper end terminating substantially at the level of the junction of the lower and upper deflector portions and 16, respectively. An auxiliary primary fuel gas inlet 31 is formed by and between the auxiliary director surface 30 and the upper end of the secondary fuel gas line 18. During use primary fuel gas supplied from the primary fuel gas line 14 through the auxiliary primary fuel gas inlet 31 to the secondary fuel gas channel 21, flows over the auxiliary director surface 30 and this flow creates a low pressure which encourages the flow of secondary fuel gas through the secondary fuel gas inlet 12 into the flow of primary fuel and air. The mechanism is the same as that described for the flow of primary fuel and air over the director surface and it makes possible the burning of waste fuel gases at pressures down to 0.5 kN/m below atmospheric pressure.

The shape of the auxiliary deflector surface is similar to that of the deflector surface 20 except that it is turned inside out and smaller.

We claim:

1. A burner for disposing of low pressure waste gas which comprises a secondary fuel gas inlet adapted to supply secondary fuel gas, which is originally at low pressure, to a combustion zone, a secondary fuel gas line, and a director tube at one end of which the secondary fuel gas inlet is situated, said director tube having an external director surface and having an internal sur- I face defining the bore of the tube, said bore being of substantial cross-sectional area throughout its length relative to the cross-sectional area of the director tube and terminating in an open end at said secondary fuel gas inlet, said bore providing a relatively large passage for conveying the secondary fuel gas from said secondary fuel gas line through the director tube to the secondary fuel gas inlet, the burner also comprising a primary fuel gas line and a deflecting baffle, said primary fuel gas line forming with said director tube a primary fuel gas inlet which is of slit form and is adapted to direct a stream of primary fuel gas, which is originally at high pressure, over the director surface towards the secondary fuel inlet, the director surface being formed from a tapered portion and a deflector portion, the tapered portion being the frustum of a cone and the deflector portion being the surface of revolution formed by the rotation of a quadrant of a circle about the axis of the secondary fuel gas line, and the curved section of the quadrant extending outwardly from said primary fuel gas inlet, whereby the flow of primary fuel gas directed by said primary fuel gas inlet over said director surface initiates flow of primary fuel gas and air towards the secondary fuel gas inlet, and said deflecting baffle being positioned in spaced opposing relation to said open end of said bore and having a circumferential portion extending outwardly beyond said tube at said open end, for deflecting secondary fuel which issues from said open end into the primary fuel gas and air and for deflecting the primary fuel gas and air so as to promote mixing and also help to stabilize the flame.

2. A burner for disposing of low pressure waste gas which comprises a secondary fuel gas inlet adapted to supply secondary fuel gas, which is originally at low pressure, to a combustion zone, a secondary fuel gas line, and a director tube at one end of which the secondary fuel gas inlet is situated, said director tube having an external director surface and having an internal surface defining the bore of the tube, said internal surface also forming an auxiliary director surface and said bore providing a passage for conveying the secondary fuel gas from said secondary fuel gas line through the director tube to the secondary fuel gas inlet, the burner also comprising a primary fuel gas line and an auxiliary primary fuel gas inlet formed between said auxiliary director surface and said secondary fuel gas line, said auxiliary inlet being adapted to direct flow of primary fuel gas over said auxiliary surface and into the bore of the director tube so as to create a low pressure zone which encourages the flow of secondary fuel gas to said combustion zone, said primary fuel gas line forming with said director tube a primary fuel gas inlet which is of slit form and is adapted to direct a stream of primary fuel gas, which is originally at high pressure, over the director surface towards the secondary fuel inlet, the director surface being formed from a tapered portion and a deflector portion, the tapered portion being the frustum of a cone and the deflector portion being the surface of revolution formed by the rotation of a quadrant ofa circle about the axis of the secondary fuel gas line and the curved section of the quadrant extending outwardly from said primary fuel gas inlet, whereby the flow of primary fuel gas directed by said primary fuel gas inlet over said director surface initiates flow of primary fuel gas and air towards the secondary fuel gas inlet.

P0405) UNITED STATES PATENT O FICE 56 CERTIFICATE OF CORRECTION Patent No 3,709,654 D d January 9, 1973 Inventor(s) DENIS HENRY DESTY et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

0n the title page, column 1, under "[30] Foreign Application Priority Data" please add Feb. 17, 1970 Great Britain Signed and sealed this 1st day of January 197A.

(SEAL) Attest:

EDWARD M.FLETGHER,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents 

1. A burner for disposing of low pressure waste gas which comprises a secondary fuel gas inlet adapted to supply secondary fuel gas, which is originally at low pressure, to a combustion zone, a secondary fuel gas line, and a director tube at one end of which the secondary fuel gas inlet is situated, said director tube having an external director surface and having an internal surface defining the bore of the tube, said bore being of substantial cross-sectional area throughout its length relative to the cross-sectional area of the director tube and terminating in an open end at said secondary fuel gas inlet, said bore providing a relatively large passage for conveying the secondary fuel gas from said secondary fuel gas line through the director tube to the secondary fuel gas inlet, the burner also comprising a primary fuel gas line and a deflecting baffle, said primary fuel gas line forming with said director tube a primary fuel gas inlet which is of slit form and is adapted to direct a stream of primary fuel gas, which is originally at high pressure, over the director surface towards the secondary fuel inlet, the director surface being formed from a tapered portion and a deflector portion, the tapered portion being the frustum of a cone and the deflector portion being the surface of revolution formed by the rotation of a quadrant of a circle about the axis of the secondary fuel gas line, and the curved section of the quadrant extending outwardly from said primary fuel gas inlet, whereby the flow of primary fuel gas directed by said primary fuel gas inlet over said director surface initiates flow of primary fuel gas and air towards the secondary fuel gas inlet, and said deflecting baffle being positioned iN spaced opposing relation to said open end of said bore and having a circumferential portion extending outwardly beyond said tube at said open end, for deflecting secondary fuel which issues from said open end into the primary fuel gas and air and for deflecting the primary fuel gas and air so as to promote mixing and also help to stabilize the flame.
 2. A burner for disposing of low pressure waste gas which comprises a secondary fuel gas inlet adapted to supply secondary fuel gas, which is originally at low pressure, to a combustion zone, a secondary fuel gas line, and a director tube at one end of which the secondary fuel gas inlet is situated, said director tube having an external director surface and having an internal surface defining the bore of the tube, said internal surface also forming an auxiliary director surface and said bore providing a passage for conveying the secondary fuel gas from said secondary fuel gas line through the director tube to the secondary fuel gas inlet, the burner also comprising a primary fuel gas line and an auxiliary primary fuel gas inlet formed between said auxiliary director surface and said secondary fuel gas line, said auxiliary inlet being adapted to direct flow of primary fuel gas over said auxiliary surface and into the bore of the director tube so as to create a low pressure zone which encourages the flow of secondary fuel gas to said combustion zone, said primary fuel gas line forming with said director tube a primary fuel gas inlet which is of slit form and is adapted to direct a stream of primary fuel gas, which is originally at high pressure, over the director surface towards the secondary fuel inlet, the director surface being formed from a tapered portion and a deflector portion, the tapered portion being the frustum of a cone and the deflector portion being the surface of revolution formed by the rotation of a quadrant of a circle about the axis of the secondary fuel gas line and the curved section of the quadrant extending outwardly from said primary fuel gas inlet, whereby the flow of primary fuel gas directed by said primary fuel gas inlet over said director surface initiates flow of primary fuel gas and air towards the secondary fuel gas inlet. 